Pyrazinone thrombin inhibitors

ABSTRACT

Compounds of the invention are useful in inhibiting thrombin and associated thrombotic occlusions and are selected from the group consisting of 3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide polymorphic crystalline Anhydrous Form B, 3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide polymorphic crystalline form Type A Monohydrate, and 3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide polymorphic crystalline form Type B monohydrate, or a pharmaceutically acceptable salt thereof.

BACKGROUND OF THE INVENTION

[0001] Thrombin is a serine protease present in blood plasma in the formof a precursor, prothrombin. Thrombin plays a central role in themechanism of blood coagulation by converting the solution plasmaprotein, fibrinogen, into insoluble fibrin.

[0002] Edwards et al., J. Amer. Chem. Soc., (1992) vol. 114, pp.1854-63, describes peptidyl a-ketobenzoxazoles which are reversibleinhibitors of the serine proteases human leukocyte elastase and porcinepancreatic elastase.

[0003] European Publication 363 284 describes analogs of peptidasesubstrates in which the nitrogen atom of the scissile amide group of thesubstrate peptide has been replaced by hydrogen or a substitutedcarbonyl moiety.

[0004] Australian Publication 86245677 also describes peptidaseinhibitors having an activated electrophilic ketone moiety such asfluoromethylene ketone or a-keto carboxyl derivatives.

[0005] R. J. Brown et al., J. Med. Chem., Vol. 37, pages 1259-1261(1994) describes orally active, non-peptidic inhibitors of humanleukocyte elastase which contain trifluoromethylketone and pyridinonemoieties.

[0006] H. Mack et al., J. Enzyme Inhibition, Vol. 9, pages 73-86 (1995)describes rigid amidino-phenylalanine thrombin inhibitors which containa pyridinone moiety as a central core structure.

SUMMARY OF THE INVENTION

[0007] The invention includes compounds for inhibiting loss of bloodplatelets, inhibiting formation of blood platelet aggregates, inhibitingformation of fibrin, inhibiting thrombus formation, and inhibitingembolus formation in a mammal, and compositions comprising a compound ofthe invention in a pharmaceutically acceptable carrier. The compositionsmay optionally include anticoagulants, antiplatelet agents, andthrombolytic agents. The compounds of the invention can be added toblood, blood products, or mammalian organs in order to effect thedesired inhibitions.

[0008] The invention also includes a compound for preventing or treatingunstable angina, refractory angina, myocardial infarction, transientischemic attacks, atrial fibrillation, thrombotic stroke, embolicstroke, deep vein thrombosis, disseminated intravascular coagulation,ocular build up of fibrin, and reocclusion or restenosis of recanalizedvessels, in a mammal.

[0009] The invention also includes a method for reducing thethrombogenicity of a surface in a mammal by attaching to the surface,either covalently or noncovalently, a compound of the invention.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

[0010] The compounds of the present invention are polymorphiccrystalline forms of the compound3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide,which has the structure

[0011] Specifically, the compounds of the invention are selected fromthe group consisting of 2-one-1-acetamide polymorphic crystallineAnhydrous Form B, 3-Fluoro-2-acetamide polymorphic crystalline form TypeA Monohydrate, and 3-Fluoro-2-acetamide polymorphic crystalline formType B monohydrate.

[0012] Some abbreviations that may appear in this application are asfollows: ABBREVIATIONS DCE 1,2-dichloroethane DMF dimethylformamide EDC1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride EtOHethanol HCl hydrochloric acid HOAc acetic acid HOAT1-hydroxy-7-azabenzotriazole iPrOH 2-propanol KOH potassium hydroxideMeOH methanol NCS N-chlorosuccinimide Pd-C palladium on activated carboncatalyst PhCH₃ toluene POBr₃ phosphorous oxybromide TEA triethylamine

[0013] The pharmaceutically-acceptable salts of the compounds of theinvention (in the form of water- or oil-soluble or dispersible products)include the conventional non-toxic salts such as those derived frominorganic acids, e.g. hydrochloric, hydrobromoic, sulfuric, sulfamic,phosphoric, nitric and the like, or the quaternary ammonium salts whichare formed, e.g., from inorganic or organic acids or bases. Examples ofacid addition salts include acetate, adipate, alginate, aspartate,benzoate, benzenesulfonate, bisulfate, butyrate, citrate, camphorate,camphorsulfonate, cyclopentanepropionate, digluconate, dodecylsulfate,ethanesulfonate, fumarate, glucoheptanoate, glycerophosphate,hemisulfate, heptanoate, hexanoate, hydrochloride, hydrobromide,hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate,methanesulfonate, 2-naphthalenesulfonate, nicotinate, nitrate, oxalate,pamoate, pectinate, persulfate, 3-phenylpropionate, picrate, pivalate,propionate, succinate, sulfate, tartrate, thiocyanate, tosylate, andundecanoate. Base salts include ammonium salts, alkali metal salts suchas sodium and potassium salts, alkaline earth metal salts such ascalcium and magnesium salts, salts with organic bases such asdicyclohexylamine salts, N-methyl-D-glucamine, and salts with aminoacids such as arginine, lysine, and so forth. Also, the basicnitrogen-containing groups may be quaternized with such agents as loweralkyl halides, such as methyl, ethyl, propyl, and butyl chloride,bromides and iodides; dialkyl sulfates like dimethyl, diethyl, dibutyl;and diamyl sulfates, long chain halides such as decyl, lauryl, myristyland stearyl chlorides, bromides and iodides, aralkyl halides like benzyland phenethyl bromides and others.

[0014] Thrombin Inhibitors-Therapeutic Uses-Method of Using

[0015] Anticoagulant therapy is indicated for the treatment andprevention of a variety of thrombotic conditions, particularly coronaryartery and cerebrovascular disease. Those experienced in this field arereadily aware of the circumstances requiring anticoagulant therapy. Theterm “patient” used herein is taken to mean mammals such as primates,including humans, sheep, horses, cattle, pigs, dogs, cats, rats, andmice.

[0016] Thrombin inhibition is useful not only in the anticoagulanttherapy of individuals having thrombotic conditions, but is usefulwhenever inhibition of blood coagulation is required such as to preventcoagulation of stored whole blood and to prevent coagulation in otherbiological samples for testing or storage. Thus, the thrombin inhibitorscan be added to or contacted with any medium containing or suspected ofcontaining thrombin and in which it is desired that blood coagulation beinhibited, e.g., when contacting the mammal's blood with materialselected from the group consisting of vascular grafts, stents,orthopedic prosthesis, cardiac prosthesis, and extracorporealcirculation systems.

[0017] Compounds of the invention are useful for treating or preventingvenous thromboembolism (e.g. obstruction or occlusion of a vein by adetached thrombus; obstruction or occlusion of a lung artery by adetached thrombus), cardiogenic thromboembolism (e.g. obstruction orocclusion of the heart by a detached thrombus), arterial thrombosis(e.g. formation of a thrombus within an artery that may cause infarctionof tissue supplied by the artery), atherosclerosis (e.g.arteriosclerosis characterized by irregularly distributed lipiddeposits) in mammals, and for lowering the propensity of devices thatcome into contact with blood to clot blood.

[0018] Examples of venous thromboembolism which may be treated orprevented with compounds of the invention include obstruction of a vein,obstruction of a lung artery (pulmonary embolism), deep vein thrombosis,thrombosis associated with cancer and cancer chemotherapy, thrombosisinherited with thrombophilic diseases such as Protein C deficiency,Protein S deficiency, antithrombin III deficiency, and Factor V Leiden,and thrombosis resulting from acquired thrombophilic disorders such assystemic lupus erythematosus (inflammatory connective tissue disease).Also with regard to venous thromboembolism, compounds of the inventionare useful for maintaining patency of indwelling catheters.

[0019] Examples of cardiogenic thromboembolism which may be treated orprevented with compounds of the invention include thromboembolic stroke(detached thrombus causing neurological affliction related to impairedcerebral blood supply), cardiogenic thromboembolism associated withatrial fibrillation (rapid, irregular twitching of upper heart chambermuscular fibrils), cardiogenic thromboembolism associated withprosthetic heart valves such as mechanical heart valves, and cardiogenicthromboembolism associated with heart disease.

[0020] Examples of arterial thrombosis include unstable angina (severeconstrictive pain in chest of coronary origin), myocardial infarction(heart muscle cell death resulting from insufficient blood supply),ischemic heart disease (local anemia due to obstruction (such as byarterial narrowing) of blood supply), reocclusion during or afterpercutaneous transluminal coronary angioplasty, restenosis afterpercutaneous transluminal coronary angioplasty, occlusion of coronaryartery bypass grafts, and occlusive cerebrovascular disease. Also withregard to arterial thrombosis, compounds of the invention are useful formaintaining patency in arteriovenous cannulas.

[0021] Examples of atherosclerosis include arteriosclerosis.

[0022] Examples of devices that come into contact with blood includevascular grafts, stents, orthopedic prosthesis, cardiac prosthesis, andextracorporeal circulation systems.

[0023] The thrombin inhibitors of the invention can be administered insuch oral forms as tablets, capsules (each of which includes sustainedrelease or timed release formulations), pills, powders, granules,elixers, tinctures, suspensions, syrups, and emulsions. Likewise, theymay be administered in intravenous (bolus or infusion), intraperitoneal,subcutaneous, or intramuscular form, all using forms well known to thoseof ordinary skill in the pharmaceutical arts. An effective but non-toxicamount of the compound desired can be employed as an anti-aggregationagent. For treating ocular build up of fibrin, the compounds may beadministered intraocularly or topically as well as orally orparenterally.

[0024] The thrombin inhibitors can be administered in the form of adepot injection or implant preparation which may be formulated in such amanner as to permit a sustained release of the active ingredient. Theactive ingredient can be compressed into pellets or small cylinders andimplanted subcutaneously or intramuscularly as depot injections orimplants. Implants may employ inert materials such as biodegradablepolymers or synthetic silicones, for example, Silastic, silicone rubberor other polymers manufactured by the Dow-Corning Corporation.

[0025] The thrombin inhibitors can also be administered in the form ofliposome delivery systems, such as small unilamellar vesicles, largeunilamellar vesicles and multilamellar vesicles. Liposomes can be formedfrom a variety of phospholipids, such as cholesterol, stearylamine orphosphatidylcholines.

[0026] The thrombin inhibitors may also be delivered by the use ofmonoclonal antibodies as individual carriers to which the compoundmolecules are coupled. The thrombin inhibitors may also be coupled withsoluble polymers as targetable drug carriers. Such polymers can includepolyvinlypyrrolidone, pyran copolymer,polyhydroxy-propyl-methacrylamide-phenol,polyhydroxyethyl-aspartamide-phenol, or polyethyleneoxide-polylysinesubstituted with palmitoyl residues. Furthermore, the thrombininhibitors may be coupled to a class of biodegradable polymers useful inachieving controlled release of a drug, for example, polylactic acid,polyglycolic acid, copolymers of polylactic and polyglycolic acid,polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters,polyacetals, polydihydropyrans, polycyanoacrylates and cross linked oramphipathic block copolymers of hydrogels.

[0027] The dosage regimen utilizing the thrombin inhibitors is selectedin accordance with a variety of factors including type, species, age,weight, sex and medical condition of the patient; the severity of thecondition to be treated; the route of administration; the renal andhepatic function of the patient; and the particular compound or saltthereof employed. An ordinarily skilled physician or veterinarian canreadily determine and prescribe the effective amount of the drugrequired to prevent, counter, or arrest the progress of the condition.

[0028] Oral dosages of the thrombin inhibitors, when used for theindicated effects, will range between about 0.01 mg per kg of bodyweight per day (mg/kg/day) to about 30 mg/kg/day, preferably 0.025mg/kg/day to 7.5 mg/kg/day, more preferably 0.1 mg/kg/day to 2.5mg/kg/day, and most preferably 0.1 mg/kg/day to 0.5 mg/kg/day (unlessspecificed otherwise, amounts of active ingredients are on free basebasis). For example, an 80 kg patient would receive between about 0.8mg/day and 2.4 g/day, preferably 2 mg/day to 600 mg/day, more preferably8 mg/day to 200 mg/day, and most preferably 8 mg/day to 40 mg/kg/day. Asuitably prepared medicament for once a day administration would thuscontain between 0.8 mg and 2.4 g, preferably between 2 mg and 600 mg,more preferably between 8 mg and 200 mg, and most preferably 8 mg and 40mg, e.g., 8 mg, 10 mg, 20 mg and 40 mg. Advantageously, the thrombininhibitors may be administered in divided doses of two, three, or fourtimes daily. For administration twice a day, a suitably preparedmedicament would contain between 0.4 mg and 1.2 g, preferably between 1mg and 300 mg, more preferably between 4 mg and 100 mg, and mostpreferably 4 mg and 20 mg, e.g., 4 mg, 5 mg, 10 mg and 20 mg.

[0029] Intravenously, the patient would receive the active ingredient inquantities sufficient to deliver between 0.025-7.5 mg/kg/day, preferably0.1-2.5 mg/kg/day, and more preferably 0.1-0.5 mg/kg/day. Suchquantities may be administered in a number of suitable ways, e.g. largevolumes of low concentrations of active ingredient during one extendedperiod of time or several times a day, low volumes of highconcentrations of active ingredient during a short period of time, e.g.once a day. Typically, a conventional intravenous formulation may beprepared which contains a concentration of active ingredient of betweenabout 0.01-1.0 mg/ml, e.g. 0.1 mg/ml, 0.3 mg/ml, and 0.6 mg/ml, andadministered in amounts per day of between 0.01 ml/kg patient weight and10.0 ml/kg patient weight, e.g. 0.1 ml/kg, 0.2 ml/kg, 0.5 ml/kg. In oneexample, an 80 kg patient, receiving 8 ml twice a day of an intravenousformulation having a concentration of active ingredient of 0.5 mg/ml,receives 8 mg of active ingredient per day. Glucuronic acid, L-lacticacid, acetic acid, citric acid or any pharmaceutically acceptableacid/conjugate base with reasonable buffering capacity in the pH rangeacceptable for intravenous administration may be used as buffers.Consideration should be given to the solubility of the drug in choosingan The choice of appropriate buffer and pH of a formulation, dependingon solubility of the drug to be administered, is readily made by aperson having ordinary skill in the art.

[0030] The compounds can also be administered in intranasal form viatopical use of suitable intranasal vehicles, or via transderrnal routes,using those forms of transdermal skin patches well known to those ofordinary skill in that art. To be administered in the form of atransdermal delivery system, the dosage administration will, or course,be continuous rather than intermittent throughout the dosage regime.

[0031] The thrombin inhibitors are typically administered as activeingredients in admixture with suitable pharmaceutical diluents,excipients or carriers (collectively referred to herein as “carrier”materials) suitably selected with respect to the intended form ofadministration, that is, oral tablets, capsules, elixers, syrups and thelike, and consistent with convention pharmaceutical practices.

[0032] For instance, for oral administration in the form of a tablet orcapsule, the active drug component can be combined with an oral,non-toxic, pharmaceutically acceptable, inert carrier such as lactose,starch, sucrose, glucose, methyl cellulose, magnesium stearate,dicalcium phosphate, calcium sulfate, mannitol, sorbitol and the like;for oral administration in liquid form, the oral drug components can becombined with any oral, non-toxic, pharmaceutically acceptable inertcarrier such as ethanol, glycerol, water and the like. Moreover, whendesired or necessary, suitable binders, lubricants, distintegratingagents and coloring agents can also be incorporated into the mixture.Suitable binders include starch, gelatin, natural sugars such as glucoseor beta-lactose, corn-sweeteners, natural and synthetic gums such asacacia, tragacanth or sodium alginate, carboxymethylcellulose,polyethylene glycol, waxes and the like. Lubricants used in these dosageforms include sodium oleate, sodium stearate, magnesium stearate, sodiumbenzoate, sodium acetate, sodium chloride and the like. Disintegratorsinclude, without limitation, starch methyl cellulose, agar, bentonite,xanthan gum and the like.

[0033] The invention also includes a method for treating an inflammatorydisease in a patient which comprises treating the patient with acomposition comprising a compound of the present invention. Suchdiseases include but are not limited to nephritis, systemic lupuserythematosus, rheumatoid arthritis, glomerulonephritis, and sacoidosis.

[0034] The invention is also a method for treating an inflammatorydisease in a patient that comprises treating the patient with acombination comprising a compound of the invention and an NSAID, e.g., aCOX-2 inhibitor. Such diseases include but are not limited to nephritis,systemic lupus, erythematosus, rheumatoid arthritis, glomerulonephritis,vasculitis and sacoidosis.

[0035] The present invention is a method for relieving pain, fever andinflammation of a variety of conditions including nephritis, systemiclupus erythematosus, rheumatoid arthritis, glomerulonephritis,sacoidosis, rheumatic fever, symptoms associated with influenza or otherviral infections, common cold, low back and neck pain, dysmenorrhea,headache, toothache, sprains and strains, myositis, neuralgia,synovitis, arthritis, including rheumatoid arthritis degenerative jointdiseases (osteoarthritis), gout and ankylosing spondylitis, bursitis,burns, injuries, following surgical and dental procedures in a patientby administering to the patient a therapeutically effective amount of acompound of the invention. Thrombin inhibitors may also be useful forthe treatment of dementia including pre-senile and senile dementia, andin particular, dementia associated with Alzheimer Disease.

[0036] In inflammatory diseases wherein fibrin formation is prominent,the fibrin may be a determinant of the pathology. Fibrin serves as amatrix onto which inflammatory cells can migrate and adhere. (seeSherman et al., 1977 J. Exp. Med. 145:76-85; Altieri et al., 1986 J.Clin. Invest. 78:968-976; Wright et al., 1983 Proc. Natl. Acad. Sci.85:7734-7738; Altieri et al., 1993 J. Biol. Chem. 268;1847-1853). Fibrinalso enhances expression of the inflammatory cytokine IL-lbeta anddecreases expression of IL-1 receptor antagonist by human peripheralblood mononuclear cells (see Perez 1995 J. immunol. 154:1879-1887). Theanticoagulants warfarin and heparin attenuate delayed-typehypersensitivity reactions and experimental nephritis in animals. (seeJasain et al., Immunopathogenesis of Rheumatoid Arthritis Eds. G. S.Panayi et al., Surrey, U K, Reedbooks, Ltd. and Halpern et al., 1965Nature 205:257-259). Enzymatic defibrination with ancrod diminishes thedegree of experimental nephritis (Naish et al., 1972 Clin. Sci.42:643-646), systemic lupus erythematosus (Cole et al., 1990 Kidney Int.37:29-35, and rheumatoid arthritis (see Busso et al., 1998 J. Clin.Invest. 102:41-50) in animals, and glomerulonephritis in man (see Kim etal., 1988 Q. J. Med. 69:879-905). Additionally, intra articularinjection of fibrin induces arthritis in rabbits immunized with fibrinDumonde et al., 1961 British Journal of Experimental PathologyXLIII:373-383), and antigen-induced arthritis in mice is exacerbated inurokinase-deficient mice wherein fibrinolysis synovial fibrin iscompromised (see Busso et al., 1998 J. Clin. Invest. 102:41-50).

[0037] In diseases where fibrin deposition is prominent such as, but notlimited to, rheumatoid arthritis, systemic lupus erythematosus,glomerulonephritis, vasculitis and sacoidosis, lowering the steady stateconcentration of fibrin by administration of a compound of the inventionwill, according to the instant invention, diminish the pathologicalinflammatory responses associated with these diseases.

[0038] Similarly, compounds of the invention will be useful as a partialor complete substitute for conventional NSAIDs in preparations whereinthey are presently co-administered with other agents or ingredients.Thus in further aspects, the invention encompasses pharmaceuticalcompositions for treating inflammatory diseases as defined abovecomprising a non-toxic therapeutically effective amount of a compound ofthe invention as defined above and one or more ingredients such asanother pain reliever including acetominophen or phenacetin; apotentiator including caffeine; an H2-antagonist, aluminum or magnesiumhydroxide, simethicone, a decongestant including phenylephrine,phenylpropanolamine, pseudophedrine, oxymetazoline, ephinephrine,naphazoline, xylometazoline, propylhexedrine, or levo-desoxyephedrine;an antiitussive including codeine, hydrocodone, caramiphen,carbetapentane, or dextramethorphan; a diuretic; a sedating ornon-sedating antihistamine. In addition the invention encompasses amethod of treating inflammatory diseases comprising administration to apatient in need of such treatment a non-toxic therapeutically effectamount of a compound of the invention, optionally co-administered withone or more of such ingredients as listed immediately above.

[0039] The instant invention also involves a novel combination therapycomprising the administration of a therapeutically effective amount ofan NSAID such as a COX-2 inhibitor in combination with a therapeuticallyeffective amount of a compound of the invention to a mammal, and moreparticularly, to a human. The combination therapy is used to treatinflammatory diseases.

[0040] The instant pharmaceutical combinations comprising a compound ofthe invention in combination with an NSAID such as a COX-2 inhibitorinclude administration of a single pharmaceutical dosage formulationwhich contains both a compound of the invention and the NSAID, as wellas administration of each active agent in its own separatepharmaceutical dosage formulation. Where separate dosage formulationsare used, the compund of the invention and the NSAID can be administeredat essentially the same time, i.e., concurrently, or at separatelystaggered times, i.e, sequentially. The “instant pharmaceuticalcombination” is understood to include all these regimens. Administrationin these various ways are suitable for the present invention as long asthe beneficial pharmaceutical effect of the compound of the inventionand the NSAID are realized by the patient at substantially the sametime. Such beneficial effect is preferably achieved when the targetblood level concentrations of each active drug are maintained atsubstantially the same time. It is preferred that the compound of theinvention and the NSAID be co-administered concurrently on a once-a-daydosing schedule; however, varying dosing schedules, such as the compoundof the invention once per day and the NSAID once, twice or more timesper day, or the NSAID once per day and the compound of the inventiononce, twice or more times per day, is also encompassed herein. A singleoral dosage formulation comprised of both the compound of the inventionand the NSAID is preferred. A single dosage formulation will provideconvenience for the patient.

[0041] The instant invention also provides pharmaceutical compositionscomprised of a therapeutically effective amount of an NSAID, or apharmaceutically acceptable salt thereof, in combination with atherapeutically effective amount of a compound of the invention, or apharmaceutically acceptable salt thereof, and a pharmaceuticallyacceptable carrier. One embodiment of the instant compositions is asingle composition adapted for oral administration comprised of atherapeutically effective amount of a COX-2 inhibitor in combinationwith a therapeutically effective amount of a compound of the inventionand a pharmaceutically acceptable carrier. The combination can also beadministered in separate dosage forms, each having one of the activeagents. If administered in separate dosage forms, the separate dosageforms are administered such that the beneficial effect of each activeagent is realized by the patient at substantially the same time.

[0042] Common NSAIDs include salicylates such as aspirin, sodiumsalicylate, choline salicylate, salicylsalicylic acid, diflunisal, andsalsalate; indoleacetic acids such as indomethacin and sulindac;pyrazoles such as phenylbutazone, oxyphenbutazone; pyrrolealkanoic acidssuch as tolmetin; phenylacetic acids such as ibuprofen, feroprofen,flurbiprofen, and ketoprofen; fenamates such as mefanamic acid, andmeclofenamate; oxicams such as piroxicam; and naphthaleneacetic acidssuch as naproxen. Cyclo-oxygenase inhibitors such as COX-1 and COX-2inhibitors are also NSAIDs.

[0043] Employing the human whole blood COX-1 assay and the human wholeblood COX-2 assay described in C. Brideau et al, Inflamm. Res. 45: 68-74(1996), herein incorporated by reference, preferably, the compounds havea cyclooxygenase-2 IC50 of less than about 2 μM in the human whole bloodCOX-2 assay, yet have a cyclooxygenase-1 IC₅₀ of greater than about 5 μMin the human whole blood COX-1 assay. Also preferably, the compoundshave a selectivity ratio of cyclooxygenase-2 inhibition overcyclooxygenase-1 inhibition of at least 10, and more preferably of atleast 40. The resulting selectivity may indicate an ability to reducethe incidence of common NSAID-induced side effects.

[0044] The inhibitor of cyclooxygenase-2 may be administered at a dosagelevel up to conventional dosage levels for NSAIDs. Suitable dosagelevels will depend upon the antiinflammatory effect of the choseninhibitor of cyclooxygenase-2, but typically suitable levels will beabout 0.001 to 50 mg/kg per day, preferably 0.005 to 30 mg/kg per day,and especially 0.05 to 10 mg/kg per day. The compound may beadministered on a regimen of up to 6 times per day, preferably 1 to 4times per day, and especially once per day.

[0045] The dosage regimen utilizing a compound of the invention incombination with the NSAID is selected in accordance with a variety offactors including type, species, age, weight, sex and medical conditionof the patient; the severity of the condition to be treated; the routeof administration; the renal and hepatic function of the patient; andthe particular compound or salt or ester thereof employed. Since twodifferent active agents are being used together in a combinationtherapy, the potency of each of the agents and the interactive effectsachieved by combining them together must also be taken into account. Aconsideration of these factors is well within the purview of theordinarily skilled clinician for the purpose of determining thetherapeutically effective or prophylactically effective dosage amountsneeded to prevent, counter, or arrest the progress of the condition.

[0046] Administration of the drug combination to the patient includesboth self-administration and administration to the patient by anotherperson.

[0047] Additional active agents may be used in combination with thecompound of the invention in a single dosage formulation, or may beadministered to the patient in a separate dosage formulation, whichallows for concurrent or sequential administration. Examples ofadditional active agents which may be employed include HMG-CoA synthaseinhibitors; squalene epoxidase inhibitors; squalene synthetaseinhibitors (also known as squalene synthase inhibitors), acyl-coenzymeA: cholesterol acyltransferase (ACAT) inhibitors; probucol; niacin;fibrates such as clofibrate, fenofibrate, and gemfibrizol; cholesterolabsorption inhibitors; bile acid sequestrants; LDL (low densitylipoprotein) receptor inducers; vitamin B₆ (also known as pyridoxine)and the pharmaceutically acceptable salts thereof such as the HCl salt;vitamin B₁₂ (also known as cyanocobalamin); β-adrenergic receptorblockers; folic acid or a pharmaceutically acceptable salt or esterthereof such as the sodium salt and the methylglucamine salt; andanti-oxidant vitamins such as vitamin C and E and beta carotene.

[0048] The thrombin inhibitors can also be co-administered with suitableanti-platelet agents, including, but not limited to, fibrinogen receptorantagonists (e.g. to treat or prevent unstable angina or to preventreocclusion after angioplasty and restenosis), anticoagulants such asaspirin, thrombolytic agents such as plasminogen activators orstreptokinase to achieve synergistic effects in the treatment of variousvascular pathologies, or lipid lowering agents includingantihypercholesterolemics (e.g. HMG CoA reductase inhibitors such aslovastatin and simvastatin, HMG CoA synthase inhibitors, etc.) to treator prevent atherosclerosis. For example, patients suffering fromcoronary artery disease, and patients subjected to angioplastyprocedures, would benefit from coadministration of fibrinogen receptorantagonists and thrombin inhibitors. Also, thrombin inhibitors enhancethe efficiency of tissue plasminogen activator-mediated thrombolyticreperfusion. Thrombin inhibitors may be administered first followingthrombus formation, and tissue plasminogen activator or otherplasminogen activator is administered thereafter.

[0049] Typical doses of thrombin inhibitors of the invention incombination with other suitable anti-platelet agents, anticoagulationagents, or thrombolytic agents may be the same as those doses ofthrombin inhibitors administered without coadministration of additionalanti-platelet agents, anticoagulation agents, or thrombolytic agents, ormay be substantially less that those doses of thrombin inhibitorsadministered without coadministration of additional anti-plateletagents, anticoagulation agents, or thrombolytic agents, depending on apatient's therapeutic Unless otherwise stated, all NMR determinationswere made using 400 MHz field strength.

[0050] Preparation of 2-Aminomethyl-3-fluoropyridine (A)

[0051] A stirred solution of 6.11 g (50.1 mmol) of2-cyano-3-fluoropyridine in 250 mL of ethanol and 12.5 mL (150 mmol) ofconc. HCl was hydrogenated over 1.90 g of 10% palladium on carbon at 40psi for 16 h. The catalyst was removed by filtration and the solventsremoved at reduced pressure. The resulting solid was diluted withacetonitrile and filtered to give 8.0 g of A as an off-white solid: ¹HNMR (CD₃OD) δ 8.48 (d, 1H, 4.8 Hz), 7.69 (td, 1H, 9.2, 1.1 Hz), 7.68(ddd, 1H, 8.8, 4.4, 4.4 Hz), 4.34 (s, 2H).

EXAMPLE 1

[0052]

[0053] Ethyl N— (ethyl carboxymethyl)oxamate (1-1)

[0054] To a suspension of ethyl glycine.HCl (38.4 g, 275 mmol ) in1,2-dichloroethane (360 mL) was added triethylamine (77.0 mL, 550 mmol)at room temperature. After stirring for 30 minutes the heterogenousmixture was cooled to 0° C. and ethyl oxalyl chloride (30.3 mL, 275 mol)was added dropwise over the course of 1 h. Upon completion of theaddition, the cooling bath was removed and the reaction was stirred atroom temperature overnight. The reaction was diluted with water (250 mL)and the layers separated. The aqueous layer was backwashed with 2portions of dichloromethane (250 mL). The combined organic layers werewashed with water (250 mL), followed by brine (250 mL), dried over MgSO₄and concentrated to give an oil 1-1 that was taken directly onto thenext step.

[0055] N-(Ethyl carboxymethyl)-N′-(2,2-dimethoxyethyl)oxamide (1-2)

[0056] To a solution of the oxamate (84.0 g, 414 mmol) 1-1 in 2-propanol(500 mL) was added aminoacetaldehyde dimethyl acetal (45.7 g, 435 mmol)in one portion. After stirring overnight at room temperature, thereaction mixture was concentrated to a thick orange oil. This thickslurry was diluted with 2-propanol (300 mL) and the solid was broken upwith a spatula. Filtration afforded a solid which was further rinsedwith an additional portion of 2-propanol. Removal of residual 2-propanolwas accomplished via high vacuum to afford a light orange solid 1-2.(89.8 g): ¹H NMR (CDCl₃) δ 7.82 (br s, 1H), 7.50 (br s, 1H), 4.41 (t,1H, 5.3 Hz), 4.24 (q, 2H, 7.1 Hz), 4.09 (d, 2H, 5.9 Hz), 3.47 (dd, 2H,5.3, 6.2 Hz), 3.40 (s, 6H), 1.30 (t, 3H, 7.1 Hz).

[0057] Ethyl 3-hydroxypyrazin(1H)-2-one-1-acetate (1-3)

[0058] A solution of the oxamide (89.8 g, 343 mmol) 1-2, acetic acid(400 mL), and conc. HCl (2 mL) was heated to reflux. After 1 h the blackreaction was concentrated to a thick oil (high vacuum employed to ensurecomplete removal of AcOH) which was diluted with EtOH (150 mL) and MeOH(150 mL). Scraping the thick black oil with a spatula inducedprecipitation of the product. The MeOH was removed via rotaryevaporation and the remaining slurry was filtered and rinsed with EtOH(200 mL) to deliver a tan solid. Recrystallization from refluxing EtOH(300 mL) afforded an off-white powder 1-3: ¹H NMR (CD₃OD) δ 6.50 (d, 1H,5.9 Hz), 6.36 (d, 1H, 5.9 Hz), 4.58 (s, 2H), 4.23 (q, 2H, 7.1 Hz), 1.28(t, 3H, 7.1 Hz). Further crude dione could be obtained uponconcentration of the mother liquor.

[0059] Ethyl 3-bromopyrazin(1H)-2-one-1-acetate (1-4)

[0060] A solution of the hydroxypyrazinone (25.0 g, 126 mmol) 1-3 andphosphorous oxybromide (37.9 g, 132 mmol) in 1,2-dichloroethane (250 mL)was heated to reflux. After 8 h the reaction mixture was treated withsat. aq. Na₂CO₃ (250 mL) and stirred for 1 h. The mixture was dilutedwith water (100 mL) and dichloromethane (100 mL), the layers wereseparated and the aqueous layer was backwashed with EtOAc (3×200 mL).The combined organics were dried (MgSO₄), and concentrated to give anoil which was stored on a high vacuum line overnite to afford brownsolid 1-4: ¹H NMR (CDCl₃) δ 7.17 (d, 1H, 4.2 Hz), 7.07 (d, 1H, 4.2 Hz),4.65 (s, 2H), 4.27 (q, 2H, 7.2 Hz), 1.31 (t, 3H, 7.2 Hz).

[0061] Ethyl3-(2,2-difluoro-2-(2-pyridylethylamino)pyrazin(1H)-2-one-1-acetate (1-5)

[0062] A solution of 4.80 g (30.4 mmol) of2,2-difluoro-2-(2-pyridyl)ethylamine, 4.24 mL (30.4 mmol) oftriethylamine and 7.93 g (30.4 mmol) of ethyl3-bromopyrazin(1H)-2-one-1-acetate 1-4 was heated to 120° C. in a sealedtube overnight in 12 mL of toluene and 4 mL of ethanol. The reaction wasconcentrated and the residue was partitioned between dichloromethane andsat. aq. NaHCO₃. The aqueous layer was backwashed with 4 portions ofdichloromethane. The combined organic layers were dried over MgSO₄ andthe solvents removed at reduced pressure to give an oil that waschromatographed on SiO₂ using 60:40 to 40:60 hexane-EtOAc to give 1-5 asa yellow solid: ¹H NMR (CDCl₃) δ 8.67 (dd, 1H, 4.8, 0.7 Hz), 7.81(ddd,1H, 7.8, 7.8, 1.7 Hz), 7.69 (dd, 1H, 7.8, 1 Hz), 7.38 (dd, 1H, 5.1,7.0 Hz), 6.86 (d, 1H, 4.8 Hz), 6.54 (br t, 1H, 5.9 Hz), 6.40 (d, 1H, 4.6Hz), 4.54 (s, 2H), 4.38 (td, 2H, 14.0, 6.4 Hz), 4.24 (q, 2H, 7.1 Hz),1.29 (t, 3H, 7.1 Hz).

[0063] Ethyl3-(2,2-difluoro-2-(2-pyridylethylamino)-6-chloropyrazin(1H)-2-one-1-acetate(1-6)

[0064] To a stirred solution of 6.81 g (20.1 mmol) of ethyl3-(2,2-difluoro-2-(2-pyridylethylamino)pyrazin(1H)-2-one-1-acetate 1-5and 2.42 g (18.1 mmol) of N-chlorosuccinimide in 100 mL of1,2-dichloroethane was heated to reflux. An additional 242 mg (1.81mmol) and 75 mg (0.56 mmol) of NCS were added to the reaction mixtureafter 1 h and 1.5 h, respectively. After 2.5 h total, the solution wascooled to room temperature and partitioned between dichloromethane (150mL) and sat. aq. NaHCO₃ (200 mL). The layers were separated and theaqueous phase was backwashed with dichloromethane (2×200 mL). Thecombined organic layers were dried over MgSO₄ and the solutionconcentrated to a volume of 10 mL. This liquid was directly loaded ontoa SiO₂ column and eluted with 65:35 to 55:45 hexane-EtOAc to give 1-6 asa yellow solid: ¹H NMR (CDCl₃) δ 8.68 (d, 1H, 4.8, Hz), 7.83 (ddd,1H,7.7, 7.7, 1.6 Hz), 7.9 (dd, 1H, 7.9 Hz), 7.40 (dd, 1H, 4.9, 7.3 Hz),6.96 (s, 1H), 6.49 (brt, 1H, 5.9 Hz), 4.89 (s, 2H), 4.38 (td, 2H,13.9,6.5 Hz), 4.26 (q, 2H, 7.1 Hz), 1.30 (t, 3H, 7.1 Hz).

[0065]3-(2,2-Difluoro-2-(2-pyridylethylamino)-6-chloropyrazin(1H)-2-one-1-aceticacid (1-7)

[0066] To a stirred solution of 7.27 g (19.5 mmol) of ethyl3-(2,2-difluoro-2-(2-pyridylethylamino)-6-chloropyrazin(1H)-2-one-1-acetate1-6 in 200 mL of methanol was added 39 niL (39.0 mmol) of 1M aq.potassium hydroxide. After 3 h the solution was acidified to pH=7 usingconc. HCl, and concentrated at reduced pressure (azeotrope with PhCH₃)to give a white solid containing potassium chloride and 1-7: ¹H NMR(CD₃OD) δ 8.64 (d, 1H, 4.8 Hz), 7.93 (ddd,1H, 7.7, 7.7, 1.5 Hz), 7.70(d, 1H, 8.0 Hz), 7.49 (dd, 1H, 5.2, 7.4 Hz), 6.80 (s, 1H), 4.67 (s, 2H),4.27 (t, 2H, 13.9 Hz).

[0067]3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide(1-8)

[0068] A stirred solution of 330 mg (0.536 mmol) of3-(2,2-difluoro-2-(2-pyridylethylamino)-6-chloropyrazin(1H)-2-one-1-aceticacid 1-7 and 160 mg (0.805 mmol) 2-aminomethyl-3-fluoropyridinedihydrochloride in 2 mL of DMF was added 128 mg (0.67 mmol) of EDC, 91mg (0.67 mmol) of HOAT and 0.30 mL (2.1 mmol) triethylamine. Afterstirring overnite, 80 mg of 2-aminomethyl-3-fluoropyridinedihydrochloride, 128 mg of EDC, 91 mg of HOAT and 0.08 mL (2.1 mmol)triethylamine were added. The reaction was stirred for an additional 24h and the volatiles were removed en vacuo. The residue was diluted withsat. aq. NaHCO₃ (10 mL) and water (15 mL) and filtered to afford a tansolid. This material was chromatographed on SiO₂ using 1:99 to 5:95MeOH—CH₂Cl₂ to give a yellow solid 1-8: ¹H NMR (CDCl₃) δ 8.67 (d, 1H,4.6 Hz), 8.32 (d, 1H, 4.6 Hz), 7.81 (dd,1H, 7.8, 6.4 Hz), 7.69 (d, 1H,7.8 Hz), 7.41-7.37 (m, 2H), 7.27-7.22 (m, 2H), 6.97 (s, 1H), 6.49 (br t,1H, 6.0 Hz), 4.93 (s, 2H), 4.66 (d, 2H, 4.0 Hz), 4.38 (td, 2H, 13.9, 6.5Hz). 1-8 is also named2-{3-[(2,2-difluoro-2-(2-pyridyl)ethyl)amino]-6-chloro-2-oxohydropyrazinyl}-N-{(3-fluoro(2-pyridyl))methyl]-acetamide.Conversion to the hydrochloride salt can be carried out by diluting theproduct with ethyl acetate (2 mL) and treating with 5 mL of 1.5M HCl inethyl acetate, followed by filtration: ¹H NMR (CD₃oD) δ 8.72 (d, 1H, 4.6Hz), 8.56 (dd, 1H, 0.9, 5.3 Hz), 8.16-8.11 (m, 2H), 7.87 (d,1H, 8.1 Hz),7.80 (ddd, 1H, 4.8, 4.8, 9.0 Hz), 7.68 (dd, 1H, 5.4, 7.2 Hz), 6.87 (s,1H), 4.95 (s, 2H), 4.74 (d, 2H, 1.1 Hz), 4.35 (t, 2H, 13.8 Hz). Twoanhydrous forms and two monohydrate forms of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide1-8 were prepared:

[0069]3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideAnhydrous Form A.

[0070] A mixture of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide1-8 (0.50 g, 1.10 mmol) and 2-methyl-1-propanol (9 mL) was heated toreflux whereby a solution resulted. After cooling to 22° C. withstirring, filtration of the subsequent mixture afforded the titlecompound (0.42 g). The Anhydrous Form A has been shown by differentialscanning calorimetry, at 5° C./min in an open container under drynitrogen flow, to have a melting point of approximately 185° C.Thermogravimetric analysis shows it to be essentially anhydrous, with nosignificant weight loss up to the melting point. The X-ray powderdiffraction pattern is characterized by principal d-spacings of 14.21,10.00, 7.14, 6.35, 5.59, 5.09, 5.01, 4.76, 4.54, 3.35, 3.30 and 2.81 Å.

[0071]3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideAnhydrous Form B.

[0072] A mixture of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide1-8 (0.50 g, 1.10 mmol) and 2-butanone (9 mL) was heated to reflux andthe resulting solution was allowed to cool to 22° C. with stirring.Filtration of the mixture then afforded the title compound (0.36 g). TheAnhydrous Form B has been shown by differential scanning calorimetry, at5° C./min in an open container under dry nitrogen flow, to have amelting point of approximately 179° C. Thermogravimetric analysis showsit to be essentially anhydrous, with no significant weight loss up tothe melting point. The X-ray powder diffraction pattern is characterizedby principal d-spacings of 16.45, 12.08, 6.81, 5.67, 5.62, 5.05, 4.08,4.04, 3.96, 3.42, 3.25 and 2.66 Å.

[0073]3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideType A Monohydrate.

[0074] A mixture of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide1-8 (2.0 g, 4.42 mmol) and aqueous acetonitrile (40 mL of 1:1) washeated to reflux whereby a solution resulted. This solution wasclarified through GF/A filter and then allowed to cool to 22° C. withstirring. Isolation of the resulting solid by filtration afforded thetitle compound (1.69 g). Type A Monohydrate has been shown by KarlFischer and thermogravimetric analyses to contain approximately 4% w/wwater, consistent with it being a monohydrate. The X-ray powderdiffractogram is characterized by principal d-spacings of 14.62, 7.34,6.70, 6.49, 5.87, 5.61, 5.54, 3.73, 3.67, 3.59, 3.43, 3.23, 3.12 and2.45 Å.

[0075]3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideType B Monohydrate.

[0076] A mixture of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamide1-8 (0.50 g, 1.10 mmol), HCl_(aq) (0.55 g of 2M aqueous solution),2-propanol (10 mL) and water (1 mL) was heated to reflux and theresulting solution was then allowed to cool to 22° C. with stirring.Filtration of the mixture then afforded the title compound (0.38 g).Type B Monohydrate has been shown by Karl Fischer and thermogravimetricanalyses to contain approximately 4% w/w water, consistent with it beinga monohydrate. The X-ray powder diffractogram is characterized byprincipal d-spacings of 14.56, 7.30, 6.96, 6.74, 6.05, 5.88, 5.70, 4.65,4.12, 3.79, 3.66, 3.58, 3.48, 3.43 and 3.01 Å.

[0077] Typical tablet cores suitable for administration of thrombininhibitors are comprised of, but not limited to, the following amountsof standard ingredients: Suggested % Ranges of Composition forExcipients in Uncoated Tablet Cores Preferred Most General Range RangePreferred Range Excipient (%) (%) (%) mannitol 10-90 25-75 30-60microcrystalline 10-90 25-75 30-60 cellulose magnesium stearate 0.1-5.00.1-2.5 0.5-1.5

[0078] Mannitol, microcrystalline cellulose and magnesium stearate maybe substituted with alternative pharmaceutically acceptable excipients.

[0079] Assays of human α-thrombin and human trypsin were performed bythe methods substantially as described in Thrombosis Research, Issue No.70, page 173 (1993) by S. D. Lewis et al. The activities shown by thisassay indicate that the compounds of the invention are therapeuticallyuseful for treating various conditions in patients suffering fromunstable angina, refractory angina, myocardial infarction, transientischemic attacks, atrial fibrillation, thrombotic stroke, embolicstroke, deep vein thrombosis, disseminated intravascular coagulation,and reocclusion or restenosis of recanalized vessels.

EXAMPLE 2

[0080] Tablet Preparation

[0081] Tablets containing 8, 10, 20 and 40 mg., respectively, of thefollowing active compounds are prepared as illustrated below(compositions A-C). Active I is one of the following compounds:3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline Anhydrous Form A,3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline Anhydrous Form B,3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type A Monohydrate, or3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type B monohydrate. Table for dosescontaining from 8 to 40 mg of the active compound Amount-mg Component AB C D Active I 8 10 20 40 Microcrystalline cellulose 37.25 100 200 200Modified food corn starch 37.25 4.25 8.5 8.5 Magnesium stearate 0.5 0.751.5 1.5

[0082] All of the active compound, cellulose, and a portion of the cornstarch are mixed and granulated to 10% corn starch paste. The resultinggranulation is sieved, dried and blended with the remainder of the cornstarch and the magnesium stearate. The resulting granulation is thencompressed into tablets containing 25.0, 50.0, and 100.0 mg,respectively, of active ingredient per tablet.

EXAMPLE 3

[0083] Tablet Preparation Exemplary compositions of Active I tablets areshown below: Component 0.25 mg 2 mg 10 mg 50 mg Active I 0.500% 1.000%5.000% 14.29% mannitol 49.50% 49.25% 47.25% 42.61% microcrystallinecellulose 49.50% 49.25% 47.25% 42.61% magnesium stearate 0.500% 0.500%0.500% 0.500%

[0084] In the table, for example, a tablet containing 2 mg of Active Iincludes 98.5 mg mannitol, 98.5 mg microcrystalline cellulose, and 1 mgmagnesium stearate. 2, 10 and 50 mg tablets were film-coated with anaqueous dispersion of hydroxypropyl cellulose, hydroxypropylmethylcellulose and titanium dioxide, providing a nominal weight gain.

[0085] Tablet Preparation Via Direct Compression

[0086] Active I, mannitol and microcrystalline cellulose were sievedthrough mesh screens of specified size (generally 250 to 750 μm) andcombined in a suitable blender. The mixture was subsequently blended(typically 15 to 30 min) until the drug was uniformly distributed in theresulting dry powder blend. Magnesium stearate was screened and added tothe blender, after which a precompression tablet blend was achieved uponadditional mixing (typically 2 to 10 min). The precompression tabletblend was then compacted under an applied force, typically ranging from0.5 to 2.5 metric tons, sufficient to yield tablets of suitable physicalstrength with acceptable disintegration times (specifications will varywith the size and potency of the compressed tablet). In the case of the2, 10 and 50 mg potencies, the tablets were dedusted and film-coatedwith an aqueous dispersion of water-soluble polymers and pigment.

[0087] Tablet Preparation Via Dry Granulation

[0088] Alternatively, a dry powder blend is compacted under modestforces and remilled to afford granules of specified particle size. Thegranules are then mixed with magnesium stearate and tabletted as statedabove.

EXAMPLE 4

[0089] Intravenous Formulations

[0090] Intravenous formulations of Active I were prepared according togeneral intravenous formulation procedures. Component Estimated rangeActive I 0.12-0.61 mg D-glucuronic acid* 0.5-5 mg Mannitol NE 50-53 mg 1N Sodium Hydroxide q.s. pH 3.9-4.1 Water for injection q.s. 1.0 mL

[0091] Exemplary compositions A-C are as follows: Component A B C ActiveI 0.61 mg* 0.30** 0.15*** D-glucuronic acid* 1.94 mg 1.94 mg 1.94 mgMannitol NF 51.2 mg 51.2 mg 51.2 mg 1 N Sodium Hydroxide q.s. pH 4.0q.s. pH 4.0 q.s. pH 4.0 Water for injection q.s. 1.0 mL q.s. 1.0 mL q.s.1.0 mL

[0092] Various other buffer acids, such as L-lactic acid, acetic acid,citric acid or any pharmaceutically acceptable acid/conjugate base withreasonable buffering capacity in the pH range acceptable for intravenousadministration may be substituted for glucuronic acid.

What is claimed is:
 1. A compound selected from the group consisting of3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline Anhydrous Form B,3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type A Monohydrate, and3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type B monohydrate, or a pharmaceuticallyacceptable salt thereof.
 2. The compound of claim 1 which is3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline Anhydrous Form B, or a pharmaceuticallyacceptable salt thereof.
 3. The compound of claim 2 having a meltingpoint of about 179° C. and an X-ray powder diffraction pattern principald-spacing of about 16.45 Å.
 4. The compound of claim 3 having X-raypowder diffraction pattern principal d-spacings of about 16.45, 12.08,6.81, 5.67, 5.62, 5.05, 4.08, 4.04, 3.96, 3.42, 3.25 and 2.66 Å.
 5. Thecompound of claim 1 which is3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type A Monohydrate, or a pharmaceuticallyacceptable salt thereof.
 6. The compound of claim 5 comprising about 4%w/w water and having an X-ray powder diffraction pattern d-spacing ofabout 14.62 Å.
 7. The compound of claim 6 comprising X-ray powderdiffraction pattern principal d-spacings of about 14.62, 7.34, 6.70,6.49, 5.87, 5.61, 5.54, 3.73, 3.67, 3.59, 3.43, 3.23, 3.12 and 2.45 Å.8. The compound of claim 1 which is3-Fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidepolymorphic crystalline form Type B Monohydrate, or a pharmaceuticallyacceptable salt thereof.
 9. The compound of claim 8 comprising about 4%w/w water and having an X-ray powder diffraction pattern principald-spacing of about 14.56 Å.
 10. The compound of claim 9 comprising X-raypowder diffraction pattern principal d-spacings of about 14.56, 7.30,6.96, 6.74, 6.05, 5.88, 5.70, 4.65, 4.12, 3.79, 3.66, 3.58, 3.48, 3.43and 3.01 Å.
 11. An oral pharmaceutical composition comprising a compoundof claim 1 and a pharmaceutically acceptable carrier.
 12. An intravenouspharmaceutical composition comprising a compound of claim 1 and apharmaceutically acceptable carrier.
 13. A method for inhibitingthrombin in blood comprising adding to the blood a composition of claim11.
 14. A method for inhibiting formation of blood platelet aggregatesin blood comprising adding to the blood a composition of claim
 11. 15.The use of a compound of claim 1, or a pharmaceutically acceptable saltthereof, in the manufacture of a medicament for inhibiting thrombin,inhibiting thrombus formation, treating thrombus formation, orpreventing thrombus formation in a mammal.
 16. A process for producing3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideAnhydrous Form A comprising the steps of: a) dissolving3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidein 2-methyl-1-propanol solvent; b) recovering the resultant solid phase;and c) removing the solvent therefrom.
 17. A process for producing3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideAnhydrous Form B comprising the steps of: a) dissolving3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidein 2-butanone solvent; b) recovering the resultant solid phase; and c)removing the solvent therefrom.
 18. A process for producing3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideType A Monohydrate comprising the steps of: a) dissolving3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidein aqueous acetonitrile solvent; b) recovering the resultant solidphase; and c) removing the solvent therefrom.
 19. A process forproducing3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamideType B Monohydrate comprising the steps of: a) dissolving3-fluoro-2-pyridylmethyl-3-(2,2-difluoro-2-(2-pyridyl)ethylamino)-6-chloropyrazin-2-one-1-acetamidein a solvent comprising aqueous hydrochloric acid, 2-propanol, andwater; b) recovering the resultant solid phase; and c) removing thesolvent therefrom.